Porting and passage arrangement for fluid pressure device



Sept. 13, 1966 w. B. EASTON 3,272,142

PORTING AND PASSAGE ARRANGEMENT FOR FLUID PRESSURE DEVICE Filed Aug. 13, 1965 5 Sheets-Sheet 1 l N VIZN 0R. MYNF E EAS'TON Sept. 13, 1966 w. B. EASTON 3,272,142

PORTING AND PASSAGE ARRANGEMENT FOR FLUID PRESSURE DEVICE Filed Aug. 15, 1965 5 Sheets-Sheet 2 United States Patent 3,272,142 PGRTIN G AND PASSAGE ARRANGEMENT FOR FLUID PRESSURE DEVICE Wayne 13. Easton, South Bend, Ind., assignor to Char- Lynn Company, Minneapolis, Minn., a corporation of Minnesota Filed Aug. 13, 1965, Ser. No. 479,424 12 Claims. (Cl. 103-130) This invention relates to fluid pressure devices of the type which utilize a gerotor and more particularly to fluid passage arrangements for such devices.

Gerotor gear sets are well known in the art and in general comprise a pair of inner and outer gears with the inner externally toothed star gear having at least one less teeth than the outer internally toothed ring gear. The star gear is eccentrically mounted relative to the ring gear and there are various combinations wherein the axes of the gears may be fixed relative to each other or there may be relative orbital movement between the axes of the gears. Of the various possible combinations which involve relative orbital movement between the gears, either gear may (1) be stationary, (2) have orbital and rotational movement, (3) have only orbital movement or (4) have only rotational movement.

It is known that when orbiting type gerotors are used for fluid pressure devices such as pumps, motors and meters, the fluid feeding and exhausting of the gerotor must be performed at the orbiting speed of the orbiting gear.

In one type of such device a valve is provided which rotates in synchronism with the orbiting of the orbiting gear and fluid passages are provided in the valve which, in general, consists of fluid feeding passage means on one of the valve and fluid exhaust passage means on the other side of the valve. This valve may be referred to as a high speed valve because it rotates at the orbital speed of the gerotor unit which is several times faster than the rotational speed of the gerotor unit.

In a second type of such device there is provided a fluid feeding and exhausting valve that rotates in synchronism with the rotational movement of the orbiting gear. As the rotational speed factor of a gerotor unit is only a fraction of the orbital speed factor, this valve may be referred to as a slow speed valve. Valve passages are provided in the slow speed valve in accordance with a known principle which causes fluid to be supplied to and exhausted from the gerotor at high speed in synchronism with the orbital speed of the gerotor despite the fact that the rotational speed of the slow speed valve is only a fraction of the orbiting speed of the gerotor unit. The slow speed valve may be referred to as operating like a commutator because its fluid feeding and exhausting characteristics in relation to an orbital type gerotor are analogous in some respects to electrical commutation. In this specification and appended claims, therefore, the words commutator and commutation mean, applied to the field of hydraulics, the particular type of slow speed valve referred to above and its particular feeding and exhausting characteristics it has in relationship to an orbital type gerotor.

Gerotor type fluid pressure devices are normally operated with high pressure fluid and, as is usually the case in designing high pressure apparatus, special consideration must be given to the sealing between the relatively rotating surfaces.

A main object of the present invention is to provide gerotor type fluid pressure devices of the high speed valve type and of the slow speed valve type having a new and improved porting and passage arrangement which facilitates the design of a more efficient sealing arrangement.

Other objects and advantages will become apparent Patented Sept. 13, 1966 from the following specification, appended claims and attached drawings.

In the drawings:

FIG. 1 is a longitudinal sectional view of a fluid pressure motor or pump of the slow speed valve type embodying the invention and taken on line 1-1 of FIG. 2;

FIG. 2 is a transverse sectional view taken on line 2-2 of FIG. 1;

FIG. 3 is a fragmentary transverse sectional view taken on line 3-3 of FIG. 1;

FIG. 4 is a longitudinal sectional view of a fluid pressure motor or pump of the high speed valve type embodying the invention and taken on line 4-4 of FIG. 5;

FIG. 5 is a transverse sectional view taken on line 5-5 of FIG. 4; and

FIG. 6 is a fragmentary transverse sectional view taken on line 6-6 of FIG. 4.

In the fluid pressure motor or pump illustrated in FIGS 1 to 3 there is provided a casing or housing made of several sections Which are a valve casing section 2, a fluid passage casing section 4 and a gerotor casing section 6. Casing sections 2 and 4 are held together in axial alignment by a plurality of circumferentially spaced bolts 8. An end cover plate 10 which serves as a side plate for the gerotor casing section 6 is provided and the casing sections 4 and 6 and cover plate 10 are held together in axial alignment by a plurality of circumferentially spaced bolts 12.

Casing section 4 is provided with inlet and outlet ports 14 and 16 which would be reversed for operation of the pump or motor in the opposite direction.

The shape of gerotor casing section 6 is generally cylindrical and annular and has a plurality of internal teeth. An externally toothed star member 18 having at least one fewer teeth than casing section 6, which may be referred to as a ring member 6, has the teeth thereof in meshing engagement with the teeth of ring member 6. Star member 18 partakes of a hypocycloidal movement and travels in an orbit about the axis of ring member 6.

The gerotor mechanism or gear set which comprises ring member 6 and star member 18 may be used as a fluid pressure motor, pump or meter and will be described more fully later on. For the present it will suflice to mention that the present invention is concerned with the valving and fluid passage means whereby fluid is supplied to and exhausted from the gerotor mechanism when the unit is operated either as a pump, a motor or meter.

Valve casing section 2 has two generally cylindrical portions 19 and 20 with portion 20 having a reduced diameter. Casing section 2 has an axially extending bore 21 and a counterbore 22, both of which bores are concentric relative to the axis 24 of ring member 6. Rotatably disposed in valve casing section 2 is a combination valve and shaft member which comprises a cylindrically shaped valve 28 which is rotatably supported in counterbore 22 and a shaft 30 which is rotatably supported in bore 21. Shaft 30 is an input shaft if the device is used as a pump and an output shaft if the device is used as a motor. The axial length of valve portion 28 is equal to the axial length of counterbore 22 so that the radial surface 32 of alve portion 28 is in sliding engagement with the adjacent radial surface 34 of casing section 4.

With reference to FIG. 3, the gerotor casing section 6, which in effect is the ring member 6, has a plurality of internal teeth 36. Externally toothed :star member 18, having at least one fewer teeth 38 than ring member 6, is disposed eccentrically in the chamber or space formed and surrounded by ring member 6. Star member 18 is moveable orbitally relative to the ring member 6 with the axis 40 of star member 18 being moveable in an orbital path about the axis 24 of ring member 6. During orbital movement of star member 18 the teeth 38 thereof intermesh with the ring member teeth 36 in sealing engagement to form expanding and contracting cells 42 which are equal in number to the number of teeth 38 of star member 18.

With further reference to FIGS. 2 and 3, a vertical centerline 44 incidentally represents the line of eccentricity for the star member 18 for that particular position of the star member relative to the ring member 6. As

used herein the term line of eccentricity means a line or plane which at all times intersects the ring and star axes 24 and 40 regardless of the position of star 18. The line of eccentricity 44, although it is an imaginary line, in effect rotates at the same speed that star 18 orbits relative to ring axis 24. During orbital movement of the star member 18, and assuming the orbital movement is clockwise, the cells 42 on the right side of the line of eccentricity 44 would be contracting and the cells 42 on the left side would be expanding. If the device is used as a motor, fluid under pressure is directed to the expanding cells and exhausted from the contracting cells. If the device is used as a motor, fiuid under pressure is directed to the expanding cells and exhausted from the contracting cells. If the device is used as a pump, fluid is sucked into the expanding cells and delivered under pressure from the contracting cells. The valving arrangement which facilitates the pumping or motor action will be described further on herein.

Casing section 4 has a bore 46 which is concentric relative to the axis 24 and is of small enough diameter so that the resulting annular face 48 which abuts gerotor casing section 6, along with cover plate 10, form sides for the gerotor chamber so that the expanding and contracting cells 42 formed between the teeth of the gerotor star and ring members 18 and 6 will be closed for all orbital positions of the star member 18.

Star member 18 has a bore 50 which is concentric relative to the teeth 38 thereof and the bore 50 is provided with a plurality of circumferentially arranged, axially extending teeth or splines 52. A bore 54 of valve 28, which is concentric relative to axis 24 and communicates with the bores 46 and 50 of casing section 4 and star 18, also has a plurality of circumferentially arranged, axially extending teeth or splines 56. A shaft 58, which may be referred to as a dogbone because of its general appearance, extends between and mechanically connects star 18 and valve 28 in driving relation. Heads 60 and 62 at opposite ends of dogbone 58 are frustospherically shaped and are provided with splines which are equal in number to and mesh with splines 52 and 56 of the star and valve members 18 and 28.

Star member 18 is eccentrically disposed relative to ring member 6, as mentioned above, and the dogbone shaft 58 is thus always in a cocked or tilted position relative to valve 28, which has the same axis 24 as ring member 6, and to the axis 40 of star member 18. In operation a star member 18 having six teeth will make one revolution about its own axis 40 for every six times the star member orbits in the opposite direction about the axis 24 of the ring member 6. Thus, the right end of the dogbone 58 has both orbital and rotational movement in common with the star member 18 while the left end of the dogbone has only rotational movement in common with valve 28.

The spline connections between dogbone 58 and valve 28 on the one hand, and between dogbone 58 and star member 18 on the other hand, are forms of universal joints which permit the dogbone to have the motion described above. When the device is utilized as a pump, star member 18 will be gyrated by a turning force applied to shaft 30 which is transmitted to star member 18 through the dogbone 58. When the device is used as a motor, the force created by the rotation of star member 18 about its own axis 40 will be transmitted through dogbone 58 to shaft 30 to cause turning of shaft 30'.

Valve 28 and easing section 4 are provided with fluid passages through which fluid is conveyed from the port 14 or 16 to the cells 42 of the gerotor and returned to the other of the :ports 14 and 16. Port 14 or 16 will be the inlet, and the other outlet port, depending on the direction of rotation desired for shaft 30. Valve 28, by reason of the dogbone connection between it and star 18, will rotate at the same speed as the star 18 but in the opposite direction from the orbiting direction of the star 18.

Inner and outer annular channels 63 and 64 are provided which are concentric relative to ring axis 24. Either or both of the channels may be in either the face 34 of casing section 4 or the face 32 of valve 28 although both channels 63 and 64 are illustrated as being in the face 32 of valve 28. Channels 63 and 64 are radially aligned respectively with axially extending passages 65 and 66 in casing section 4 which have respective fluid communication with -inlet and outlet ports 14 and 16.

With reference to FIGS. 1 and 2, valve 28 has a plurality of radially extending, circumferentially arranged and spaced grooves which are illustrated herein as a set of six grooves 68 which intersect and are in fluid communication with annular channel 63 and a set of six grooves 70, alternately spaced relative to grooves 68, which intersect and are in fluid communication with annular channel 64. In the fluid pressure device illustrated the grooves 68, and the grooves 70, are equal in number to the number of teeth 38 on the star 18.

Casing section 4 has a plurality of generally axially extending, circumferentially arranged and spaced passages 72 illustrated as being seven in number which is equal to the number of teeth 36 of the ring member 6. Passages 72 open into the radial face 34 of easing section 4 which face slidingly engages the radial face 32 of valve 28.

Upon rotation of valve 28, each of the grooves 68 and 70 thereof successively registers in fluid communication with each of the passages 72 in casing section 4. Fluid is supplied to and withdrawn from the gerotor through passages 72 which terminate at points which constitute junctions (see FIG. 3) between the teeth 36 of ring member 6.

Assuming that the fluid pressure device is functioning as a motor, pressurized fluid may be introduced through port 14 from where it would flow to passage 65, into annular channel 63 to all of the grooves 68 in valve 28, certain of the passages 72 in casing section 4 on the left side of the line of eccentricity 44 as viewed in FIG. 2, and certain gerotor cells 42 which for an instant, as viewed in FIG. 3, are on the right side of the line of eccentricity 44. The expansion of the cells 42 on the right side of the line of eccentricity 44 causes star 18 to orbit in a counterclockwise direction and causes collapsing of the cells 42 on the left side of the line of eccentricity 44. Fluid from the collapsing cells 42 flows through casing passages 72 on the left side of the line of eccentricity 44, as viewed in FIG. 3, through grooves 70 on the right side of the line of eccentricity as viewed in FIG. 2, through annular channel 64 to passage 66 and out port 16. The above description of fluid flow is only for an instantaneous condition in that the line of eccentricity 44 rotates about the axis 24 of ring member 6. As long as pressurized fluid is admitted through port 14, however, the pressurized fluid will always be admitted to cells 42 on the same side of the line of eccentricity 44 and fluid will always 'be exhausted on the other side of said line.

During orbiting of star 18 about ring member axis 24, the star rotates in the opposite direction about its own axis 40 at a slower speed. The ratio between the orbiting and rotating speeds is dependent upon the ratio between the ring and star member teeth. If that ratio is seven to six as illustrated herein, the rotating speed of the star will be one-sixth of its orbiting speed. By reason of the dogbone connection between star 18 and valve 28, valve 28 rotates at the same speed and in the same direction as star 18. Valve 28 is a commutating L type valve in that it rotates at the same speed that star 18 rotates but it functions to supply and exhaust fluid to and from the gerotor at the orbiting frequency of the star.

The construction described above wherein (1) the annular channels 63 and 64 are either in the flat valve face 32 or the flat oasing surface 34 of easing section 4 and (2) the sets of grooves 68 and 70 are in the flat valve face 32, has two main advantages. that sealing only has to be provided between one set of relatively moveable surfaces which are the valve surface 32 and the casing surf-ace 34. The second advantage is that surfaces 32 and 34 are flat surfaces and the Wear that results from their sliding engagement can be automatically and continuously compensated for by merely providing biasing means (not shown) for urging valve 28 towards casing surface 34 so that the inevitable wearing that will occur will not result in a loss of contact between the surfaces 32 and 34.

The fluid pressure motor or pump illustrated in FIGS. 4 to 6, which is the high speed valve type, has several parts which are identical to corresponding parts of the device shown in FIGS. 1 to 3 and will not be described again. The parts of the device of FIGS. 1 to 3 which are are identical to corresponding parts in FIGS. 4 to 6 are the casing sections 2 and 4, ring 6 and cover plate 10. The parts of the second device which are the same as corresponding parts of the first device have the same reference numerals associated therewith.

Referring to FIGS. 4 to 6, there is rotatably disposed in valve casing section 2 a combination valve and shaft member which comprises a cylindrically shaped valve 128 which is rotatably supported in counterbore 22 and a shaft 130 which is rotatably supported in bore 21. Shaft 130 is an input shaft if the device is used as a pump and an output shaft if the device is used as a motor. The axial length of valve portion 128 is equal to the axial length of counterbore 22 so that the radial surface 132 of valve portion 128 is in sliding engagement with the adjacent radial surface 34 of casing section 4.

The star 118 of the second device has one fewer teeth 138 than the ring member 6 and differs from the star 18 of the first device only by having a cylindrical bore 158 that is concentric to the axis 140 thereof instead of a splined bore.

Expanding and contracting cells 142 are formed between star 118 and ring 6 and star .118 has the same relationship and the same orbital and rotational movements relative to ring 6 as star 18 of the first device.

Rotatably disposed in star bore 150 is an eccentric member 160 which has a bore 161 which is concentric relative to the ring axis 24. Valve 128 has a shaft 158 which is concentric relative to the ring axis 24 and is disposed in the bore 46 of casing section 4. Shaft 158 has a concentric extension 159 of reduced diameter which fits in the bore 161 of eccentric member 160 and key means 162 are provided to facilitate a driving connection between shaft extension 159 and eccentric member 160.

With the driving connection between valve 128 and star 118 described, valve 128 will be caused to rotate in synchronism with the orbiting speed of the star 118 instead of the rotating speed of the star as in the device shown in FIGS. 1 to 3.

Valve 128 and casing section 4 have fluid passages through which fluid is conveyed from the port 14 or 16 to the cells 142 of the gerotor and returned to the other of the ports 14 or 16. Port 14 or 16 will be the inlet, and the other the outlet port, depending on the direction of rotation desired for shaft 130. Valve 128, by reason of the eccentric drive connection between it and star 118, will rotate in synchronism With the orbiting movement of star 118.

In accordance with the invention, the second device illustrated could be provided with annular channels in One advantage is the face 34 of casing section 4 similar to annular channels 63 and 64 in valve 28 of the first device but the valving arrangement shown in FIGS. 4 and 5 is a preferred embodiment of the invention. Face 132 of valve 128 has two generally annular channels 163 and 164 which are in respective fluid communication with casing inlet and outlet passages 65 and 66. The outer circumference of channel 164 is defined by an outer circumferential wall 180. Wall means separate channels 163 and 164 which includes two semicircular walls 181 and 182 with wall 181 being formed so that casing passages 72 are tangent to the radially inward side thereof and wall 182 being formed so that the casing passages 72 are tangent to the radially outward side thereof. Walls 181 and 182 are connected by short walls 183 and 184 which extend radially, are diametrically opposed and have widths equal to the diameters of passages '72. The inner circumference of channel 163 is defined by the periphery of a circular surface portion 185 of valve surface 132.

With the valve arrangement described, annular channel 163 is in constant fluid communication with casing inlet passage 65, assuming port 14 is the inlet port, and with the casing passages 72 on the left side of the line of eccentricity 144 as viewed in FIG. 5. Annular channel 164 is in constant fluid communication with casing outlet passage 66 and casing passages 72 on the right side of the line of eccentricity 144.

Upon rotation of valve 128, channel portions 163 and 164 thereof successively register in fluid communication with each of the passages 72 in casing section 4. Assuming that the fluid pressure device is functioning as a motor, pressurized fluid may be introduced through port 14 from Where it would flow to passage 65, into annular channel 163 to certain of the passages 72 in casing section 4 on the left side of the line of eccentricity 144, as viewed in FIG. 5, and certain gerotor cells 124 which for an instant, as viewed in FIG. 6, are 011 the right side of the line of eccentricity 144 as viewed in FIG. 5. The expansion of the cells 124 on the right side of the line of eccentricity 144 causes star 118 to orbit in a counterclockwise direction and causes collapsing of the cells 124 on the left side of the line of eccentricity 144. Fluid from the collapsing cells 124 flows through casing passages 72 on the left side of the line of eccentricity 144, as viewed in FIG. 6, into annular channel 164 and through passage 66 to outlet port 16. The above description of fluid flow is only for an instantaneous condition in that the line of eccentricity 144 rotates about the axis 24 of ring member 6. As long as pressurized fluid is admitted through port 14, however, the pressurized fluid will always be admitted to cells 124 on the same side of the line of eccentricity 144 and fluid will always be exhausted on the other side of said line.

Wall portions 183 and 184 have the same widths as the diameters of passages 72 to facilitate the change from pressure to exhaust and exhaust to pressure for each passage 72 during each cycle of operation. If the device is operated as a motor and pressurized fluid is introduced through port 14, star 118 will orbit in a counterclockwise direction as viewed in FIG. 6 and valve 128 will rotate in a clockwise direction as viewed in FIG. 5. With star 118 in the position illustrated, the passage 72 shown covered by valve wall 183 has at that instant just finished exhausting fluid from gerotor cell A to annular channel 164 and in the next instant, after valve 128 has rotated a slight distance further in a clockwise direction, will supply fluid from annular channel 163 to expanding gerotor cell B. A few degrees later in the cycle valve wall 184 will stop the flow of fluid from channel 163 to cell C and begin exhausting fluid from that cell to channel 164. Wall portions 183 and 184 cooperate successively with the passages 72 in the manner described to always maintain pressure in the gerotor cells on one side of the line of eccentricity 144 and exhaust fluid from the cells on the other side of the line of eccentricity.

The construction described above wherein the annular channels 163 and 164 are in the fiat valve face 132 of valve 128 has two main advantages. One advantage is that sealing only has to be provided between one set of relatively moveable surfaces which are the valve surface 132 and the casing surface 34. The second advantage is that surfaces 132 and 34 are flat surfaces and the wear that results from their sliding engagement can be automatically and continuously compensated for by merely providing biasing means (not shown) for urging valve 128 towards casing surface 34 so that the inevitable wearing that will occur will not result in a loss of contact between the surfaces 132 and 34.

While two embodiments of the invention are described here, it will be understood that other modifications are possible, and that such modifications, including a reversal of parts, may be made without departure from the spirit and scope of the invention as defined in the claims.

What I claim is:

1. In a fluid pressure device, a casing, an internally toothed ring member defining the outer wall of a chamber, a cooperating externally toothed star member having fewer teeth than said ring member disposed eccentrically in said chamber, one of said members having orbital movement about the axis of the other of said members and one of said members having rotational movement about its own axis, the teeth of said members intermeshing in sealing engagement to form expanding cells on one side of the line of eccentricity between said members and contracting cells on the other side of said line during relative movement between said members, a valve rotatably disposed in said casing, drive means operatively connecting said valve to one of said members for rotation of said valve in synchronism with one of said movements of one of said members, said casing and said valve having mutually engaging plane surfaces, fluid inlet and outlet passages extending from the exterior of said casing to said plane surface of said casing, passage means in said casing which form circumferentially spaced openings in said plane surface of said casing and extend therefrom to said ring member chamber for communication with said cells, fluid feeding and exhausting recess means in said plane surface of said valve having constant communication respectively with said fluid inlet and outlet passages, said valve recess means upon relative movement between said valve and casing being sequentially communicable with each of said casing passages to effect communication between said inlet ports and the expanding cells on one side of said line of eccentricity and between said outlet port and said contracting cells on the other side of said line of eccentricity.

2. A fluid pressure device according to claim 1 wherein said drive means connects said valve to one of said members having rotational movement for rotation in synchronism with said rotational movement.

3. A fluid pressure device according to claim 2 including a first annular channel in one of said plane surfaces which has fluid communication with said fluid inlet passage and said fluid feeding recess, and a second annular channel in one of said plane surfaces which has fluid communication with said fluid outlet passage and said fluid exhausting recess.

4. A fluid pressure device according to claim 3 wherein at least one of said annular recesses is in said valve surface.

5. A fluid pressure device according to claim 3 Wherein both of said annular recesses are in said valve surface.

6. A fiuid pressure device according to claim 2 wherein said fluid feeding and exhausting recess means includes a series of circumferentially arranged fluid feeding recesses and a series of circumferentially arranged fluid exhausting recesses arranged alternately relative to said fluid feeding recesses.

7. A fluid pressure device according to claim 2 wherein said ring member is fixed relative to said casing and said star member has orbital and rotational movement relative to said ring member.

8. A fluid pressure device according to claim 1 wherein said drive means connects said valve to one of said members having orbital movement for rotation in synchronism with said orbital movement.

9. A fluid pressure device according to claim 8 wherein for any position of said valve said valve feeding and exhausting recess means have constant fluid communication with casing passages on opposite sides of said line of eccentricity.

10. A fluid pressure device according to claim 9 wherein said feeding and exhausting recess means are separated by two generally semicircular walls with one of said walls being radially outwardly from said casing passage opening and the other of said walls being radially inwardly from said casing passage openings.

11. A fluid pressure device according to claim 10 wherein said semicircular walls are connected by two radially extending walls each having the same width as the diameters of said casing passage openings.

12. A fluid pressure device according to claim 8 wherein said ring member is fixed relative to said casing and said star member has orbital and rotational movement relative to said ring member.

References Cited by the Examiner UNITED STATES PATENTS Re. 25,126 2/1962 Charlson 91-56 Re. 25,291 12/1962 Charlson 91-56 2,758,573 8/1956 Krozal 91-56 2,989,951 6/1961 Charlson 123 8 3,087,436 4/1963 Dettlof et a1. 10330 3,215,043 11/1965 Huber 230 3,233,524 2/1966 Charlson 9156 MARK NEWMAN, Primary Examiner.

W. J. GOODLIN, Assistant Examiner. 

1. IN A FLUID PRESSURE DEVICE, A CASING, AN INTERNALLY TOOTHED RING MEMBER DEFINING THE OUTER WALL OF A CHAMBER, A COOPERATING EXTERNALLY TOOTHED STAR MEMBER HAVING FEWER TEETH THAN SAID RING MEMBER DISPOSED ECCENTRICALLY IN SAID CHAMBER, ONE OF SAID MEMBERS HAVING ORBITAL MOVEMENT ABOUT THE AXIS OF THE OTHER OF SAID MEMBERS AND ONE OF SAID MEMBERS HAVING ROTATIONAL MOVEMENT ABOUT ITS OWN AXIS, THE TEETH OF SAID MEMBERS INTERMESHING IN SEALING ENGAGEMENT TO FORM EXPANDING CELLS ON ONE SIDE OF THE LINE ECCENTRICITY BETWEEN SAID MEMBERS AND CONTRACTING CELLS ON THE OTHER SIDE OF SAID LINE DURING RELATIVE MOVEMENT BETWEEN SAID MEMBERS, A VALVE ROTATABLY DISPOSED IN SAID CASING, DRIVE MEANS OPERATIVELY CONNECTING SAID VALVE TO ONE OF SAID MEMBERS FOR ROTATION OF SAID VALVE IN SYNCHRONISM WITH ONE OF SAID MOVEMENTS OF ONE OF SAID MEMBERS, SAID CASING AND SAID VALVE HAVING MUTUALLY ENGAGING PLANE SURFACES, FLUID INLET AND OUTLET 